Foot control for artificial legs



1950 J. G. CATRANIS 2,530,286

FOOT CONTROL FOR ARTIFICIAL LEGS Filed Jan. 28, 1948 2 Sheets-Sheet 1Jill-2:1- jl: E

1 I 1 45 39 40 43 INVENTORZ 3a (701 Cafra ns,

Patented Nov. 14, 1950 FOOT CONTROL ARTIFICIAL LEGS John G. Catranispsyracuse, N.MY.'

Application January 28, 1948, Serial No. 4,856

6 Claims. (Cl. 3;;2)

-above the knee amputees embodying a knee lock which normally locks theknee joint from bending, and particularly to a control for the kneelock, which control is operated progressively by dorsiflexion of thefoot, and also by the movement of the leg structure about a .forward andrearward horizontally extending axis between it and the foot structure,and by both of. these movements occurring during the walking cycle. Theinvention consists in the novel features and in the combinations andconstructions hereinafter set forth and claimed.

In describing this invention, reference is had to, the accompanyingdrawings in which like characters designate corresponding parts in allthe views.

Figure 1 is a side elevation of an artificial leg embodying this footcontrol.

Figure 2 is an elevation looking to the left in Figure 1.

Figure 3 is a fragmentary elevation looking to r the left in Figure 1showing the operation of the operating member for the knee look by themovement of the leg about a forwardly and rearwardly extending axiswithin the foot structure.

-Figure .& is a schematic view of the knee lock mechanism.

The numeral l designates the upper leg structure which is provided witha stump receiving socket 2, and a knee cap bracket or frame 3.

, 4=designates the lower leg structure, this being hinged at 5 to theknee cap frame 3 by a, knee joint shaft or pin. 6 designates the foot towhich the lower leg structure is hinged at l by an ankle joint.

The lower leg structure includes a frame memher or tibia 8 which has abifurcated head 9 at its upper end mounted on the knee joint pin 5, and

, the tibia at its lower end is' connected to the foot by the anklejoint I.

I designates the knee lock -mechanism as a whole. The mechanism hereshown is vhydraulic and includes a cylinder ll mounted by a strap [2 onthe tibia 8, and a piston I4 in the cylinder having its rod pivoted atI6 to a link I! which, in turn, is pivoted at its upper end at I8 to abearing bracket l9 rigid with the frame 3. The radius of the pivot l8,relative to the knee joint pin 5, is such that during bending of theknee, the joint I8 moves in an upwardly curved arc and hence, tends topull the piston l4 upward. The piston is also formed with a tail rod 20.The cross sectional areas of the two rods l5 and is such as to equalizethe pressure areas on opposite sides ofthe piston.

I This invention relates to artificial legs for 7 The cylinder II isconnected in a closed hydraulic system including a by-pass around thepiston fromv the upper to the lower end of the :cylinder including pipes21, 22, 23 and 24, in 1 which islocated a control member, as a valve 25.

I The valve includes a normally closed, self-closing valve member 26pressed against its seat by a .spring 21 and-operable off its seatdifferent .dis- 1. .tancesby an operating member 28 which'ais actu-"ated byrthe flexions of the foot, as will hereinafter appear. 7

The hydraulic system further includes a second by-pass around the valve25, this having a selfclosing check valve 30 therein arranged to checkthe flow of fluid from the upper end of the cylinder to the lower,but topermit comparatively free flow from the lower end of the cylinder to theupper. This second by-pass includes pipe 3| forming extension of thepipe 2|, and pipe 32 connected to the pipe 24 at the lower end of thecylinder.

When the knee flexes, as indicated by the broken line position of thesocket and lower leg structure in Figure 1, the piston pulls upwardly inthe cylinder l I, thus tending to move the fluid through the controlvalve to the lower end of the cylinder. The fluid can not flow unlessthe foot is flexing and hence, the control valve member 26 open. Whenthe leg, straightens, the

piston [4 tends to move downward in the cylinder H and circulates thefluid through the -by-passaround the control valve controlled by thecheck valve which opens when the hydraulic E fluid is moved by thepressure of the piston M downward in the cylinder II.

The operating member 28 is actuated by the flexions of the foot, as willnow be described. The foot includes an upper tarsus section 35, a'lowertarsus section 36, these sections being hinged together by aiorwardlyand rearwardly extending horizontal hinge pin 31. The foot furtherincludes a metatarsal section 38 hinged at 39 on a horizontal axis tothe forward end of the lower tarsus section 36, the metatarsal sectioncarrying a phalanges section 40 at its front end and hinged or pivotedat 40A thereto. The upper tarsus section is provided with a rigidforward extension 4| extending over the metatarsal section and spacedtherefrom at its front end to permit pivotal movement of the metatarsalsection 38 about its axis or hinge 39. There is a block 42 of yield ingmaterial between the front end of the extension 4| and the metatarsalsection, and also a spring 43 acts on the phalanges section to resistpivotal. movement thereof relative to the. meta- 3 tarsal section. Theupper and lower tarsus sections constitute the rear portion of the footstructure to which the lower leg is connected by the ankle joint to theupper tarsus section.

The foot structure per se forms no part of this invention, and theinvention relates primarily to the operation of the control for the kneelock. The foot control for the knee lock is operated by thedorsiflexion, or the movement of the metatarsal section about =its pivot39, and by the movement of the upper tarsus 35 about the forward andrearward axis 3'! between it and the lower tarsus section 35.

The foot control includes a lever 451 extencling rearwardly from themetatarsal section along the lower tarsus section 36 and in a plane atone'si'de of the vertical plane of the rhinge axis iiLand a motiontransmitting link 48 connecting the rear end of the lever 45 and theoperating member 28, the link 48 having a clevis 39 at its upper endwhich is pivoted at 50'to the operatingmember 28.

The operating member 28 is connected Zto the stem of the valve 26 bya'lost motion, as .a pin and slot connection arranged topermit the valve26 to open under sudden or excessive pressure relative to the operatingmember 28 and thus actas a relief valve.

The upper-leg structure also includes a fibula link 52 pivoted at its.upper .end at 53 to .the bracket Hlatv the lowerend of the stump socket:I,

eccentric to and below the knee joint pin 5, and

ing azstepandicreates a lost motion gap in the fibula. Duringithe'taking of Ithe step and the knee action, the fibula, duetto itspivotal connection, moves downward, and then when.the legisragain'straightened,:returnsthe foot .to its normal positionidueto thefrictionofthe slip joint taking .up the :lost motion. The fibula formsno part of this inventionand, as its name implies, simulates thefunction of a natural fibula.

The valve member226 is .closed and hence, the

knee lock locked when theleg'is in straight or .extended position andthe foot normal, or not flexed about the metatarsal joint '39 and thejoint 40A.

In operation, during a walking cycle, assume :that the subject isinsstanding position with the feet .offthei-natural and artificial legstogether. and starts Walking by taking astepwithitheartificial leg. Heshifshis weight to the 'natural leg, lifts the straight artificiallegand 'footoff the ground,

' swings it forward about the 'hip joint stiff legged fashion, andplants'the heel of the artificial'foot on the ground, the knee jointbeing locked. The body progresses forward "during this action so thatthe natural leg is inclining rearward from the hip. I-Ie then'shiftshisweightonto the'arti- ,ficial leg. The artificial foot then pivots as aunit about the-ankle joint so that the foot comes flat on the ground;this operation being permitted by the'fibula link. Be swings up on thetoe of the artificial foot, the phalanges section pivoting at thejoint45a against the action of the spring 43. The body in the meantime isprogressing forward'and hence the artificial leg moves toward and into arearward inclined position from the body, and the artificial foot pivotsabout the metatarsal joint 39, operating :theactuator 28 progressivelyto open the valve 26,- letting the leg begin to bend slightly at theknee joint at the time the foot of the natural leg, which has beenswinging forward to take a new step, is about to be planted on theground. The subject may hasten the knee unlocking operation byvoluntarily swinging the artificial leg about the forward and rearwardpivot 31, as shown in Figure 3, or unlock the knee look at any time byswinging the leg about the pivot 27 Whilethe artificial foot is on theground. The opening of the valve :26, when the natural foot is abouttobe planted on the ground, causes the step to be taken by the naturalleg with a slight limp. When the natural foot is planted on the floor,and the weight transferred thereto,

the artificial leg, slightly bent at the knee, is lifted off the groundand it swings as a pendulum from rearward inclined position to forwardinclined position to take another step. The artificial leg alsostraightens at the knee joint, the fluid passing freely past the checkvalve 3|! during the .downwardmovement of the piston '14.

The operating :member 28 is additionally actuated'bythe movement of theupper tarsus section about the pivot or hinge13'lby an inward swinging.of the artificial leg about :the pivot I relative to the foot whenplanted on the floor.

"Theleg and foot here illustrated is for the right leg in which themovement of the artificial leg is .to the left about the hinged axis 31of the right artificial leg, as seen in Figure '3.

:The artificial :leg, when fitted to the amputee, i arranged so that thefoot is straight, or toes outward in accordance withltherequirements ofthe amputee. :Hence, during the walking cycle the movements about bothaxes or hinges 39 and .31 .mayitake place during that .cycle and hence,

the valve 26 opens progressively and involuntarily. The-knee may beunlocked at anytime by the subject voluntarilyswinging-the leg laterallyabout the pivot .31 when the foot is on the floor or ground.

In descending inclines and steps, the amputee placesthefoot of theartificial leg, while theleg is extended, onto the next'lower step, andwhen he applies-his weight thereto and the body progressesxforward bythe taking of a step with the natural;leg,='the flexing of the footoccurs partly opening the throttle valve 26 and releasing'the kneejoint,'permitting theknee to bendunder the restrained flow of fluid pastthe partly open valve;26 whileithe footiof the natural leg isbeingplaced .on .the stepbelow that on which the artificial-foot is located.With the foot of thenatural legon thestep, and the artificial legfiexedwith .thefoot on the next upper step, the amputee lifts the artificialleg by lifting up on the hip joint, .or lifting-upon the stump, and-theartificial leg being unlocked at the knee joint, will swing'to- I wardstraightened position into a position to be planted in its straightposition on'the step next lowerto that on .which' the natural'footisplanted.

"However, in-ascending inclines or steps, the amficial legwhich'includes a-stump-receiving socket,

a lower leg structure hinged .by a knee joint to the lower end of thesocket, a foot hinged to the lower leg structure by an ankle joint, anda knee lock mechanism carried by the lower leg structure and operable tolock the knee joint against hinging movement; the knee lock mechanismincluding a control member and an operating member therefor, the controlmember being in position to lock the knee joint when the leg is instraight or extended position, the foot including a rear portion and ametatarsal section hinged on a transverse axis to the rear portion ofthe foot, the ankle joint being between the lower leg structure and therear portion of the foot, and motion transmitting means between themetatarsal section and the operating member to transmit the relativehinging movement of the metatarsal section and the rear portion of thefoot to which it is hinged, to the operating member.

2. A foot control for the knee lock of an artificial leg which includesa stump receiving socket, a lower leg structure hinged by the knee jointto the lower end of the socket, a foot hinged to the lower leg structureby an ankle joint, and a knee lock mechanism carried by the lower legstructure and operable to lock the knee joint against hinging movement;the knee lock mechanismincluding a control member and an operatingmember therefor, the control member being in position to lock the kneejoint when the leg is in straight or extended position, the footincluding an upper tarsus section and a lower tarsus section hingedtogether on a forward and rearward horizontal hinged axis, the anklejoint being between the lower leg structure and the upper tarsussection, and motion transmitting connections between the foot and theoperating member to transmit the relative hinging movement of the upperand lower tarsus sections to the operating member.

3. A foot control for the knee lock of an artificial leg which includesa stump receiving socket, a lower leg structure hinged by the knee jointto the lower end of the socket, a foot hinged to the lower leg structureby an ankle joint, and a knee lock mechanism carried by the lower legstructure and operable to lock the knee joint against hinging movement;the knee lock mechanism including a control member and an operatingmember therefor, the control member being in position to lock the kneejoint when th leg is in straight or extended position, the footincluding an upper tarsus section, a lower tarsus section hinged to theupper by a forwardly and rearwardly extending horizontal hinged joint,and a metatarsal section hinged to the front end of the lower tarsussection, and motion transmitting connections between the metatarsalsection and the operating member to actuate it upon relative hingingmovements of the metatarsal section and the lower tarsus section, and ofthe.

upper and lower tarsus sections.

4. A foot control for the knee lock of anartificial leg which includes astump receiving socket, a lower leg structure hinged by a knee joint tothe lower end of the socket, a foot hinged to the lower leg structure byan ankle joint, and a knee lock mechanism carried by the lower legstructure and operable to normally look the knee joint against hingingmovement when the leg is in extended or straightened position; the kneelock mechanism including a control member self-returnable to normalposition and an operating member therefor, the foot including an upper 6tarsus section, a lower tarsus section hinged to the upper by aforwardly and rearwardly extending horizontal hinged joint, and ametatarsal section hinged to the front end of the lower tarsus section,a lever pivoted to the metatarsal section and extending lengthwise ofthe metatarsal section and the lower tarsus section at one sid of thevertical plane of the hinged joint between the tarsus sections, and amotion transmitting link connected at its opposite ends to said leverand to the operating member to operate the same on pivotal movement ofthe lever about its own axis upon relative pivotal movement of themetatarsal section and the lower tarsus section about the hingedconnection between it and the lower tarsus section.

5. A foot control for the knee lock of an artificial leg which includesa stump receiving socket, a lower leg structure hinged by the knee jointto the lower end of the socket, a foot hinged to the lower leg structureby an ankle joint, and a knee lock mechanism carried by the lower legstructure and operable to lock the knee joint against hinging movementwhen the leg is in straight or extended position; the foot includingupper and lower tarsus sections and a metatarsal section hinged to thefront end of the lower tarsus section, the knee lock mechanism includinga control member and an operating member therefor, the control memberbeing normally in position to lock the knee joint when the leg is instraight or extended position, a lever pivotedto the metatarsal sectionand a motion transmitting link between it and the operating member toactuate the same upon relative movement of the metatarsal section andthe tarsus sections about the hinged joint of the metatarsal section.

6. A foot control for the knee lock of an artificial leg which includesa stump receiving socket, a lower leg structure hinged by a knee jointto the lower end of the socket, a foot hinged to the lower leg structureby an ankle joint, and a knee lock mechanism carried by the lower legstructure and operable to lock the knee joint against hinging movementwhen the leg is in straight or extended position, the knee lockmechanism including a control member and an operating member therefor;the foot including an upper tarsus section, a lower tarsus sectionhinged tothe upper by a forwardly and rearwardly extending hinged joint,and a metatarsal section hinged to the front end of the lower tarsussection by a transverse hinged joint, a lever hinged to the metatarsalsection and extending rearwardly along one side of the tarsus section atone side of the vertical axis of the joint between the tarsus sections,

and a motion transmitting link between said lever and the operatingmembers.

JOHN G. C'ATRANIS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 41,033 Vaughan Dec. 22, 1863FOREIGN PATENTS Number Country Date 530,623 France Oct. 6, 1921 530,887France Oct. 12, 1921

